I seem to be having the same problem. I used a commercial Stain Treatment about 10 days ago ($25.00/lb) The stain is now back- it is not a metal stain because I used a little of the Stain Treatment on the stain and it immeadiately disappeared- I then tested a small area with Metal Out and it did nothing. So I am now ordering Vit C but do you have any idea why the stain came back. FC-5; CC-0; TA-120; PH- 7.5; Calcium- 100; CYA- 50.

The stain treatment I used is be Haviland Chemical and I am certain it is ascorbic acid powder. 24 hr after treatment I started bringing my FC up and then adjusted my pH and TA. 5 days after I did the treatment I had t go out of town and it was raining so I added a bag of ultra shock and some polyquat. I cam back 2 days later to the stain- my water has been consistent- with0 CC when testing but I cant figure out why the stain. Any ideas?

I am going to follow your directions when I get my ascorbic acid in. It is hot, humid and sunny during the dayand rainy in the late afternoon and early evening. Should I worry about algae when I lower my chlorine to 0 for 48 hrs/ I will use Polyquat but should I just use 3-4 oz as prevention or more as if I am traeating an algae problem. Sorry if these questions seem stupid - I have a tendency to over think or over do.